Wellbores for the production of hydrocarbon fluid generally are provided with steel casings and/or liners to provide stability to the wellbore wall and to prevent undesired flow of fluid between the wellbore and the surrounding earth formation. A casing generally extends from surface into the wellbore, whereas a liner may extend only a lower portion of the wellbore. However in the present description the terms “casing” and “liner” are used interchangeably and without such intended difference.
In a conventional wellbore, the wellbore is drilled in sections whereby each section is drilled using a drill string that has to be lowered into the wellbore through a previously installed casing. In view thereof the wellbore and the subsequent casing sections decrease in diameter with depth. The production zone of the wellbore therefore has a relatively small diameter in comparison to the upper portion of the wellbore. In view thereof it has been proposed to drill a “mono diameter” wellbore whereby the casing or liner to be installed is radially expanded in the wellbore after lowering to the required depth. Subsequent wellbore sections therefore may be drilled at a diameter larger than in the conventional wellbore. If each casing section is expanded to the same diameter as the previous section, the wellbore diameter may remain substantially constant with depth.
In applications whereby the tubular element needs to be radially expanded in compressive contact with a previously installed tubular element to form a tubular connection, it is generally required that the tubular connection is sealed so as to withstand differential fluid pressures between the interior and the exterior of the connection. Several attempts have been made to provide such sealing connection.
US 2010/0122820 A1 discloses an expandable tubular including a tubular body and a plurality of seals having a corrugation on an external surface of the tubular body. During expansion, the corrugations of the seals straighten out. However, expansion of the tubular body needs to be controlled accurately since there is a risk that the seals are damaged if too strongly compressed against the previous tubular element, and a risk of inadequate sealing functionality if too loosely compressed against the previous tubular element.
US 2012/0205872 A1 discloses an assembly with a seal between an expandable first tubular and a second tubular whereby an annular member is attached to the first tubular, the annular member having a groove on the outer surface in which a seal member is disposed. The seal member is configured to be expandable radially outward into contact with an inner wall of the second tubular. It is a drawback of the known assembly that the seal member protrudes outside the groove and is therefore vulnerable to damage during running-in into the wellbore.
Other expandable tubular assemblies with sealing rings arranged in recesses are known from US patent applications US2002/0148612, US2002/0175474 and US2013/0248209.
The system and method according to the preamble of claims 1 and 15 are known from US patent application US2005/057005, which discloses the use of lip type seals that are arranged in a generally cylindrical recess that remains generally cylindrical after expansion with the risk of inadequate sealing if the seals are too loosely compressed against the outer tubular element.
It is an object of the invention to provide an improved sealing tubular connection that overcomes the drawbacks of the prior art.